A direct descendent of the HK416, the MR556A1 is a semi-automatic rifle developed by Heckler & Koch as a premium level commercial/civilian firearm with match rifle capability. Like the HK416, the MR556A1 is a major product improvement over conventional AR-type carbines and rifles.

The MR556A1 uses the HK proprietary gas piston operating system, employing a piston and a solid operating “pusher” rod in place of the gas tube normally found in AR15/M16/M4-style firearms.

This method of operation virtually eliminates malfunctions that are common to direct impingement gas systems since hot carbon fouling and waste gases do not enter the receiver area. This is the same key feature critical to the success of the HK416 rifles used by leading military and law enforcement customers.

The MR556A1 is manufactured in the USA using American and German made components. The MR556A1 uses many of the same assemblies and accessories originally developed for the HK416 including the HK free-floating four-quadrant rail system.

The HK Free Floating Rail System (FFRS) handguard has four MIL-STD-1913 “Picatinny” rails and allows all current accessories, sights, lights, and aimers used on M4/M16-type arms to be fitted to the MR Series. The HK rail system can be installed and removed with simple tools and returns to zero when reinstalled.

The MR556A1 also has a Picantinny rail machined into the top of its upper receiver for mounting optics and mechanical sights. Unlike earlier prototypes, major subassemblies, including the MR556A1 upper receiver/barrel assembly, are fully interchangeable with other high quality AR-style firearms. MR556A1 upper receiver kits can be used to retrofit competing legacy AR systems.

Like the famous HK416, the MR556A1 uses a German-made barrel produced by Heckler & Koch’s famous cold hammer forging process. The highest quality steel is used in this unique manufacturing process producing a barrel that provides superior accuracy and long service life.

But unlike the HK416, the MR556A1 does not use a chrome-lined barrel. Chrome-lining can sometimes mask bore imperfections and negatively affect accuracy. For the new series of Heckler & Koch semi-automatic MR rifles, HK designers and engineers believe best accuracy comes with an unlined bore.

Used with the HK Free Floating Rail System, the barrel does not touch the handguard, ensuring the barrel is truly free-floating for maximum accuracy.

The unchromed barrel has an internal profile of 6 lands and grooves with a 1 in 7 inch (178 mm) twist. It is also moderately “swagged” with a slightly smaller internal diameter at the muzzle end than the chamber end. This feature has a positive effect on bullet accuracy and velocity. The thick, heavy contour 16.5-inch MR556A1 barrel also contributes to its excellent accuracy.

A precise enhanced two-stage trigger adds significantly to the accuracy of the MR5556A1 and an extended latch charging handle makes operating the rifle with a telescopic sight easier. The retractable buttstock can be locked into a solid, non-moving position by tightening an Allen screw in the bottom of the stock. Special target rifle takedown pins ensure the upper and lower receivers are firmly mated for accurate performance.

Designed to function with a wide variety of high quality 5.56 x 45 mm ammunition, the MR556A1 uses a C.I.P. dimensioned chamber (a chamber with dimensions specified by the Commission Internationale Permanente).The MR556A1 also functions reliably with most quality Caliber .223 Remington ammunition.

The MR556A1 is being produced with the same commitment to quality as German-made HK firearms. By using joint U.S./German manufacturing, Heckler & Koch leverages the relative strengths of two continents to make the preeminent AR-type firearm, combining the designs innovations of the USA and Germany into one new product.

Category : Tactical Rifles

Action : Semi-Automatic

Caliber : 223 Remington/5.56 NATO

Barrel Length : 16.5"

Capacity : 30+1

Trigger : Two Stage

Safety : Lever

OAL : 33.9"-37.68"

Weight : 8.6 lbs

Stock Description : Adjustable Black

Metal Finish : Black

Reviewed by
4
customer

Correct- best there is,
June 15, 2015

I had to scrape up change to afford this rifle - but you're right- it is the best and worth the price of admission. Thanks Impact

By
Packer from
WA

Best AR on the market,
June 14, 2015

Ignore the clown comparing this superior weapon to a heap of crap like an SKS. The two systems are "the same" in the way that a small block chevy v8 is the same as a small block ford: they are both engines with 8 cylinders and pushrods. The MR556 might not be a 416 but it's as close as it gets. Is it pricey? Of course, but so are POF, LWRC and the like, but this HK is the semi-auto version of the one issued to operators. If you want a toy, get a bushmaster, if you want a high quality, durable, reliable, and accurate weapon, made by the best firearms manufacturer on the planet, this is the best AR for the money and the best in the high end bracket.

By
SKS is crap from
Germany

Best feeling AR on the market,
August 25, 2013

Bought this gun last year as somewhat of an impulse purchase. Read about it during development and knew HK was a great brand, but mostly purchased this because it was pretty rare. I have several different ARs and have shot many more, but this gun is the most solid, crisp shooting AR I have experienced. You have to shoot it to believe the feel. It is completely solid, and has a beautiful trigger.
I am a die-hard LMT and KAC fan, but I do feel this gun is more solid than either. Never gets dirty, never had a malfunction. It is heavy and does not have many gimmicks, but I think this would be a great gun to have if I ever deployed again.
Also, the magazines from HK are the best made AR mags available. They are heavy, but solid and very reliable. Buy one and see.

By
Engineer from
Texas

The best civilian AR style rifle on the market...,
January 24, 2013

After long debate I broke down and purchased an Hk MR556A1. The price was a hold up for me, but after shooting one, I knew, " it must be mine". This is truly the best built AR type rifle I have ever handled. It is a sub MOA gun, if the operator can do their part. After buying it and comparing it to LWRC or Adams piston AR's the only thing they have in common is the look. I have never shot an AR that stays cleaner or requires less lubrication to keep it running. Even Larry Vickers says this is the Rifle that All other piston AR's will ever be compared to.

This firearm ships to your local gun dealer/gun store (FFL dealer). Use our easy 'FFL SEARCH' in the menu bar at the top of the page. They will gladly provide you with a copy of their license, and charge you a small transaction fee. No Sales Tax will be due (Except in Utah and Idaho).

Once we have a copy of their license, we can ship the gun to your local dealer, you then drop by their place, fill out the required paperwork/background check, and take the gun home. We can walk you thru the procedure and help you locate a qualified dealer- just call or email for more information.

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